1. Field of the Invention
This invention concerns an injector for feeding additives into a polymer melt stream.
2. Summary of the Related Art
Devices for feeding one liquid medium into another are known. U.S. Pat. No. 5,176,448 describes a device for mixing fluid media in which a liquid additive is conveyed through a channel having a 90.degree. deflection to an outlet at the side. The side outlet opens directly into the middle of the countercurrent main stream of another liquid medium directly upstream of a biscuit located inside of the main stream conduit and forming an annular gap with it for the passage of the liquids.
U.S. Pat. No. 4,753,535 describes a device for mixing two liquid media, whereby most of the main stream of the one liquid medium is conveyed through a flow channel containing static mixing elements and arranged at the center of the main stream conduit. At a right angle to the direction of flow, the second liquid medium is fed directly into the flow channel through a lateral feed port.
E. Henglein, Lexikon Chemische Technik [Lexicon of Chemical Technology], 1988, page 267, describes an injector for continuous mixing of two gases, where one component of the mixture is fed centrally into a mixing zone at a high rate while the second gas stream enters the zone through the remaining annular gap. Due to the high flow rate and the difference in flow rates at the point of entry, there is a great deal of turbulence prevailing in the mixing zone.
European Patent Application No. 838,259 describes a device for adding additives to a stream of a highly viscous liquid having one feed element for each additive to be supplied. Each feed element has a feed channel for the additive running across the direction of flow that opens into a feed port of an annular tube sheet within the main stream conduit. The tube sheet serves as additive distributor.